1. Field
A scroll compressor is disclosed herein.
2. Background
Generally, a scroll compressor is a compressor configured to suck and compress a refrigerant using a structure including an orbiting scroll that performs an orbital motion with respect to a fixed scroll, in a state in which a fixed wrap of the fixed scroll is engaged with an orbiting wrap of the orbiting scroll. In this case, a compression chamber including a suction chamber, an intermediate pressure chamber, and a discharge chamber is consecutively moved between the fixed wrap and the orbiting wrap.
Such a scroll compressor is more advantageous than other types of compressors with respect to vibration and noise, as it performs a suction process, a compression process, and a discharge process consecutively. Behavior characteristics of the scroll compressor may be determined by a type of the fixed wrap and the orbiting wrap. The fixed wrap and the orbiting wrap may have any shape. However, generally, the fixed wrap and the orbiting wrap have the form of an involute curve which can be easily processed. The involute curve has a path formed by the end of a string when the string wound on a basic circle having an arbitrary radius is unwound. In the case of using such an involute curve, a capacity change rate is constant because a thickness of the wrap is constant. For a high compression ratio, a number of turns of the wrap should be increased. However, in this case, a size of the scroll compressor may be also increased.
In the orbiting scroll, an orbiting wrap may be formed at a surface of a plate formed in a disc shape. A boss portion may be formed on a surface of the plate on which the orbiting wrap has not been formed, to be connected to a rotational shaft that drives the orbiting scroll to perform an orbital motion. Such structure is advantageous in that a diameter of the plate may be reduced, because the orbiting wrap is formed on an almost entire area of the plate. However, with such structure, a point of application at which a repulsive force of a refrigerant is applied during a compression operation, and a point of application at which a reaction force to attenuate the repulsive force is applied are spaced from each other in a vertical direction. This may cause unstable behavior of the orbiting scroll during the operation, resulting in severe vibration or noise.
In order to solve such problems, a scroll compressor shown in FIG. 1 has been proposed. The scroll compressor of FIG. 1 has a structure in which a coupling point between a rotational shaft 1 and an orbiting scroll 2 is formed on the same surface as an orbiting wrap 2a. In such a scroll compressor, as a point of application at which a repulsive force of a refrigerant is applied, and a point of application at which a reaction force to attenuate the repulsive force is applied are the same, a phenomenon in that the orbiting scroll 2 is tilted may be solved.
An Oldham ring 4, configured to prevent rotation of the orbiting scroll 2, is installed between the orbiting scroll 2 and a fixed scroll 3. The orbiting scroll 2 and the Oldham ring 4 perform a relative motion with respect to each other in a state in which key recesses 2b and keys 4a are coupled to each other. The Oldham ring 4 induces the orbiting scroll 2 to perform an orbital motion. The key recesses 2b of the orbiting scroll 2 and the keys 4a of the Oldham ring 4 are coupled to each other with a tolerance gap δ1 of about 10˜30 μm, so that the orbiting scroll 2 may perform a sliding motion with respect to the Oldham ring 4.
However, the conventional scroll compressor may have the following problems. As shown in FIG. 2, due to the tolerance gap δ1 between the key recesses 2b of the orbiting scroll 2 and the keys 4a of the Oldham ring 4, a rotational moment occurs when the orbiting scroll 2 performs the orbital motion. Due to such rotational moment, offset is generated at a specific portion between the orbiting wrap 2a of the orbiting scroll 2 and the fixed wrap 3a of the fixed scroll, that is, at both sides of an arc compression surface based on contact points formed by a tangent line and the arc compression surface, the tangent line being drawn from a center of a rotational shaft coupling portion of the orbiting scroll 2 toward the arc compression surface. Due to the offset of the orbiting scroll 2 in such offset section β, interference A occurs between the orbiting wrap 2a and the fixed wrap 3a, as shown in FIG. 3. Due to such interference A, a leakage gap B between the orbiting wrap 2a and the fixed wrap 3a occurs at other portions. This may cause compression loss.